Adobe Support can configure a referrer filter at the CDN (Content Delivery Network) level so that Dynamic Media content is only served to websites on your list of permitted websites for the domain.
This feature requires that you use the out-of-the-box CDN that is bundled with Adobe Experience Manager Dynamic Media. Any other custom CDN is not supported with this feature. To activate hot link protection, an Administrator must create a Adobe Customer Care support ticket to request the configuration change to your Dynamic Media account. There is no additional cost for activating hot link protection.